Vo2 Max doesn't seem to be moving?

Hey

I've had my Fenix 6x pro now for over 2 and a bit weeks now and love it, however, my Vo2 Max isn't working. It's not moving at all. I work out every day with intense workouts from riding, running, strengths and cardio. However, my Vo2 Max is still saying 42 fair, which I think is wrong.

My wife has got my Venu and only goes for one/two dog walks every day and her Vo2 max is changing all the time (Now is better than mine) which don't make sense with the amount of workout and training I'm doing. Am I missing something?

Any help would be fantastic, thanks.